Mutagenic potential of laboratory chlorinated river water.

Sample water was taken from a river and chlorinated at a concentration of 5 mg 1(-1) chlorine for 20 h in the laboratory in order to examine the effect of chlorination on the mutagenic potential of organic extracts that were recovered using XAD-2 resin and diethyl ether. It was found that the XAD extracts recovered from the river water showed per se strong mutagenic activity, in the presence of S-9 mix, towards Salmonella typhimurium TA 1538. When the mutagenic activity of the XAD extracts was related to the initial water volume, chlorination increased both the direct-acting and the S-9 dependent mutagenic activity. This suggests that chlorination produced de novo direct-acting and S-9 dependent mutagens and/or increased pre-existing mutagenic activities. In addition, in this study XAD extracts recovered from chlorinated and unchlorinated river water were divided into a neutral, basic and acidic fraction respectively. When the mutagenic activity of each fraction was related to the initial water volume, the neutral fraction showed the most marked increase in mutagenic activity with, and without, the S-9 mix in the chlorinated river water.